seanbudd · Jan 18, 2023 · Nov 9, 2021 · Nov 10, 2021 · Nov 10, 2021 · Nov 10, 2021
@@ -733,3 +733,8 @@ def initializeDetectionData():
 		"seikantk",
 		isSeikaBluetoothDeviceMatch
 	)
+
+	# albatross
+	addUsbDevices("albatross", KEY_SERIAL, {
+		"VID_0403&PID_6001",  # Caiku Albatross 46/80
+	})
@@ -0,0 +1,9 @@
+# A part of NonVisual Desktop Access (NVDA)
+# This file is covered by the GNU General Public License.
+# See the file COPYING for more details.
+# Copyright (C) 2023 NV Access Limited, Burman's Computer and Education Ltd.
+
+"""Braille display driver for Tivomatic Caiku albatross 46 and 80 displays."""
+
+# Imported here so that braille._getDisplayDriver can import
+from .driver import BrailleDisplayDriver  # noqa: F401
@@ -0,0 +1,156 @@
+# A part of NonVisual Desktop Access (NVDA)
+# This file is covered by the GNU General Public License.
+# See the file COPYING for more details.
+# Copyright (C) 2023 NV Access Limited, Burman's Computer and Education Ltd.
+
+"""Threads for Tivomatic Caiku Albatross braille display driver.
+Classes:
+- L{ReadThread}; manages reconnection retries and works as a trigger
+for read operations excluding initial connection establishment
+- L{RepeatedTimer}; timer to check periodically if data needs to be sent
+to display to keep connection. If display gets nothing within approximately
+2 seconds, it falls back to "wait for connection" state.
+"""
+
+import ctypes
+import serial
+
+from ctypes import byref
+from ctypes.wintypes import DWORD
+from logHandler import log
+from serial.win32 import (
+	ERROR_IO_PENDING,
+	EV_RXCHAR,
+	GetLastError,
+	SetCommMask,
+)
+from threading import (
+	Event,
+	Thread,
+	Timer,
+)
+from typing import Callable
+
+from .constants import KC_INTERVAL
+
+
+class ReadThread(Thread):
+	"""Controls most of read operations and tries to reconnect when needed."""
+
+	def __init__(
+			self,
+			readFunction: Callable[[], None],
+			disableFunction: Callable[[], None],
+			event: Event,
+			dev: serial.Serial,
+			*args,
+			**kwargs
+	):
+		"""Constructor.
+		@param readFunction: Handles read operations and reconnection.
+		@param disableFunction: Called on connection failure.
+		@param event: Exit thread when set.
+		@param dev: Port object.
+		"""
+		super().__init__(*args, **kwargs)
+		self._readFunction = readFunction
+		self._disableFunction = disableFunction
+		self._event = event
+		self._dev = dev
+
+	def run(self):
+		data = dwEvtMask = DWORD()
+		log.debug(f"{self.name} started")
+		while not self._event.isSet():
+			# Try to reconnect if port is not open
+			if not self._dev.is_open:
+				log.debug(
+					f"Calling {self._readFunction.__name__}, port {self._dev.name} not open"
+				)
+				self._readFunction()
+				if not self._dev.is_open:
+					log.debug(
+						f"Sleepin {KC_INTERVAL} seconds, port {self._dev.name} not open"
+					)
+					self._event.wait(KC_INTERVAL)
+					continue
+			# If any of I/O function fails, it should not crash the thread.
+			try:
+				if not SetCommMask(self._dev._port_handle, EV_RXCHAR):
+					# Exiting
+					if self._event.isSet():
+						break
+					self._disableFunction()
+					log.debug("SetCommMask failed")
+					continue
+				result = ctypes.windll.kernel32.WaitCommEvent(
+					self._dev._port_handle,
+					byref(dwEvtMask),
+					byref(self._dev._overlapped_read)
+				)
+				if not result and GetLastError() != ERROR_IO_PENDING:
+					if self._event.isSet():
+						break
+					self._disableFunction()
+					log.debug("WaitCommEvent failed")
+					continue
+				result = ctypes.windll.kernel32.GetOverlappedResult(
+					self._dev._port_handle,
+					byref(self._dev._overlapped_read),
+					byref(data), True
+				)
+				if result:
+					log.debug(f"Calling function {self._readFunction.__name__} for read")
+					self._readFunction()
+				else:
+					if self._event.isSet():
+						break
+					log.debug(f"GetOverLappedResult failed {ctypes.WinError()}")
+					self._disableFunction()
+		# Considering situation where "albatross_read" thread is about to read
+		# but writing to display fails during it - or vice versa - AttributeError
+		# or TypeError might raise.
+			except (OSError, AttributeError, TypeError):
+				if self._event.isSet():
+					break
+				else:
+					self._disableFunction()
+					log.debug("", exc_info=True)
+		log.debug(f"Exiting {self.name}")
+
+
+class RepeatedTimer:
+	"""Repeating timer.
+	Timer is used to check if data needs to be sent to display to keep
+	connected.
+	"""
+
+	def __init__(
+			self,
+			interval: float,
+			feedFunction: Callable[[], None]
+	):
+		"""Constructor.
+		@param interval: Checking frequency
+		@param feedFunction: feeds display with data if needed
+		"""
+		self._interval = interval
+		self._timer = Timer(self._interval, self._run)
+		self._feedFunction = feedFunction
+		self.is_running = False
+		self.start()
+
+	def _run(self):
+		self.is_running = False
+		self.start()
+		self._feedFunction()
+
+	def start(self):
+		if not self.is_running:
+			self._timer = Timer(self._interval, self._run)
+			self._timer.start()
+			self.is_running = True
+
+	def stop(self):
+		self._timer.cancel()
+		self.is_running = False